Dependence of Powder Characteristics on Die Wall Friction during Ejection of Compacts from Die Cavity

Abstract

ABSTRACT

The evaluation of ejection behavior is important to the final formability of green compact because both the ejection and the compression in the powder die compaction are affected by die wall friction. In other words, there is a hysteretic relationship between the lateral pressure and compacting pressure. In this paper, the effect of powder characteristics on the ejection die wall friction was studied using a powder model that considers the hardness and shape of the powder. The ejection behavior was classified on the basis of the powder’s characteristics coefficient drawn from the model. Next, the influence of the particle size distribution, in addition to that of the hardness and shape of the powder, on the ejection behavior was shown.